Neurotransmitters made up of amino acids that are active not only in the brain but, like microcosmic keys fitting into tiny keyholes in the cells of the body, act like "bits of brain" that float throughout the body and help unlock a cells memory.
small molecules that circulate throughout the body and bind to cells in the emotional center of the brain and to many organs, especially cells of the gut and immune system; these molecules are used in mind-body communications